How to combine two sets of strings in Perl 6?

Question

Is there an idiomatic way or inline method for concatenating two Sets strings?

Here is what I want:

 > my Set $left = <start_ begin_>.Set set(begin_ start_) > my Set $right = <end finish>.Set set(end finish) > my Set $left_right = ($left.keys X~ $right.keys).Set set(begin_end begin_finish start_end start_finish) 

Or, if there are more than two:

 > my Set $middle = <center_ base_>.Set > my Set $all = ([X~] $left.keys, $middle.keys, $right.keys).Set set(begin_base_end begin_base_finish begin_center_end begin_center_finish start_base_end start_base_finish start_center_end start_center_finish) 

Answer 1

You can use the reduce function to go from an arbitrary number of sets to one set with everything concatenated in it:

 my Set @sets = set(<start_ begin_>), set(<center_ base_>), set(<end finish>); my $result = @sets.reduce({ set $^a.keys X~ $^b.keys }); say $result.perl # => Set.new("start_base_end","begin_center_finish","start_center_finish", "start_center_end","start_base_finish","begin_base_end", "begin_center_end","begin_base_finish") 

It seems to me clean.